Apparatus for controlling and measuring the concentration of solutions



KLINE 2,586,169

ION OF SOLUTIONS Aug. 4, 1947 Feb. 19, 1952 R. v.

APPARATUS FOR CONTROLLING AND MEASURING THE CONCENTRAT Filed INVENTORRAYMOND V. K LIN E 12%;? ATTORK Patented F eb. 19, 1952 URING THECQNCENTRAIII ON OF 'SOLU- TIONS Raymond V. Kline,

inneapoHs Minn assignor to Patent Managemen t Incl, Minneapolis,

Minn., a corporation of Minnesota Application August 4; 1947,:Se1iarN0'. 7 65,867 1 oaim. (o1. 17"5 1'83 Y My invention relates toapparatus for controllin and measuring the concentration ofsolu tionsand has for an object to provide apparatus by means of which suchresults may be auto matically procured.

An object of the invention resides providing apparatus using electricalmeans for controlling and measuring the concentration of solutions.

A still further object of the invention resides in providing apparatusin which the concentration of the solution is determined by themeasurement of the electrical resistance or of the impedance of thesolution. g

An object of the invention resides in providing apparatus in whichvariations in the resistance or impedance of the solution due'totemperature changes is automatically compensated for.

A further object of the invention resides in providing a unit insertableinto the solution whose concentration is to be measured or controlled,said unit having electrodes making electrical contact with the solutionand a compensating resistor subject to the temperature of the solution.a p

Another object of the invention resides in causing separate currents toflow through said resistor and through said electrodes, at least thecurrent through said electrodes being alternating current, in rectifyingsaid current or currents, in combining currents corresponding to thecurrents flowing through said resistor and electrodes and in utilizingthe resultant of said currents for the purpose of control and/ormeasurement.

A still further object of the invention resides in providing a loadingdevice to which the circuits for said currents are connected and inconnecting said circuits to said loading device in such a manner thatthe currents oppose one another.

An object of the invention resides in providing a meter operated by theresultant of the currents combined.

A still further object of the invention resides:

in providing a control device such as an electrically operated valveoperable by the resultant of the currents combined. Y

Other objects of the invention reside in the novel combination andarrangement of parts and in the details of construction hereinafterillustrated and/or described.

In the drawings:

Fig. l is a wiring diagram of an apparatus for controlling theconcentration of solutions and illustrating an embodiment of myinvention.

Fig. 2 is a longitudinal elevationalsectional View of the control unitofthe invention.

of the same an insulating bushing I6.

The invention includes a control unit II) which is shown in detail inFig. 2. This unit consists of a: cable H having three conductors I2, I3,and I l; Theunit proper includes a sleeve I5 constructed of metal whichhas disposed at one end This bushing is pressed securely into the sleeveI5 and snugly fits about the outer covering I! of the cable II forming afluid tight connection between the same. At the other end of the sleeveI5 is provided another insulating bushing I8 which likewise is pressedinto the sleeve I5 and protrudes outwardly therefrom. This bushing hasmounted in it a tubule l9 which is pressed into the said bushing andforms a fluid tight connection therewith. The end 2| of the tubule I9 isclosed and has attached to it one terminal 22 of atemperaturecompensating resistor 23. The composition of the resistor 23is such that the resistance of said resistor varies with temperature inthe same manner and to the same extent that the impedance of thesolution at a certain concentration varies with temperature change. Theotherterminal 24 of this resistor is con nected to the conductor I4 ofcable I I. Conductor I3 is connected to the tubule I9 which forms oneelectrode of the con trol unit III, while conductor I2 is connected tothe sleeve I5 which forms theother electrode ofsaid unit. Parallelingthe resistor 23 an adjustable resistor 50 which is .;connected at oneend to the conductor I3 and at itsother end to conductor I 4. 7

Electrical power for operation of the invention is procured'from asuitable source of alternating current which has connected to it twoconductors 25 and 26. The conductor 26 is connected to "aswitch 21'which in turn is connected t another conductor 28; Conductor 25 isconnected to a fuse 29' which in turn is connected to another conductor3|; Conductors 28 and 3i have connected to them other conductors I I Iand I09 which will be'subsequently referred'to. The invention utilizes atransformer 32 which has a primary 33 provided with a tap 34. The saidtransformer also has two secondaries 35 and 36. One end of the primary33 of transformer 32 is connected to the conductor 3| while theconductor 28'is connected to the tap 34 of the said primary,

The unit I0 isadapted to'be inserted into the solution'whoseconcentration is to be determined and the impedance of the liquidbetween the electrodes I9 and IB-compared with the resistance of theresistor 23. For this purpose a rectifier tube 31' is 'ernployed whichhas a cathode 38 and two plates 39=and 4|. In conjunction with this tubetwo transformers-42 and 43 are employed. The

transformer 42 has a primary 44 and a secondary 45 while the transformer43 has a primary 46 and a secondary 41. The conductor I4 of cable II isdirectly connected to one end of the primary 44 of transformer 42. Theother end of the primary 44 of this transformer is connected by means ofa conductor 48 to one end of the secondary 35 of the transformer 32. Theother end of this secondary is connected to the conductor I3. Thesecondary 35 of transformer 32 has a tap 49 which is connected by meansof a conductor I with the one end of the primary 46 of transformer 43.The other end of said primary is connected to the conductor I2.Connected across the conductors I3 and I4 and in parallel with theresistor 23 is an adjustable resistor 50. This resistor is used tocompensate for variations in the impedance across the electrodes I5 andI9. It will thus be seen that alternating current voltage is impressedacross the resistor 23 and the portion of the solution between theelectrodes I9 and I5 and that the current through this resistance andthis impedance is separately stepped up by the two transformers 42 and43 and separately rectined by the rectifier 31.

The cathode 38 of the tube 31 is connected to a conductor 52. The plates39 and 4| of this tube are connected by means of conductors 53 and 54 toone side of each of the secondaries 45 and 41 of the transformers 42 and43. The other sides of these secondaries have conductors 55 and 56connected to them. A condenser 51 is connected by means of a conductor58 to the conductor 55 and by means of a conductor 59 to the conductor52. In a similar manner a condenser 6| is connected by means of aconductor 62 to the conductor 56 and by means of a conductor 63 to theconductor 52. Paralleling the condenser 51 is a resistor 64 which isconnected by means of a conductor 65 with the conductor 55. The saidresistor is further connected by means of a conductor 66 with aconductor 52. Paralleling the condenser 6| is a potentiometer II one endof which is connected by means of a conductor 12 to the conductor 52.The other end of the said potentiometer is connected by means of aconductor 13 to the conductor 56. The potentiometer H has a movablecontact 14 which is connected by means of a conductor to a resistor 16.This resistor is in turn connected by means of a conductor 11 to acondenser 18 which is connected by means of a conductor 19, to theconductor I09. A conductor 68 is connected to conductor 55 and toconductor 19.

The output of the rectifier 31 is fed to an amplifier tube 8| which hasa plate 82, a grid 83 and a cathode 84. A conductor 85 is connected tothe conductor 11 between the resistor 16 and the condenser 18 and alsoto the grid 83 of the tube 8I. The cathode 84 of the said tube isconnected by means of a conductor I19 with the conductor 19 and by meansof the same to the conductor I09 previously referred to.

My invention is particularly useful in controlling "the concentration ofa solution and for this purpose an electrically operated valve 86 isemployed. This valve comprises a valve body 81 having a valve seat 88and a valve head 89 cooperating therewith. An inlet pipe 9I is connectedto a source of a concentrated solution of the substance in solutionwhile an outlet pipe 92 leads the same to the receptacle in which theconcentration of the solution is being controlled. Valve head 89 has avalve stem 93 extending upwardly therefrom which is attached to the core94' of a solenoid 95. This solenoid includes a winding 96 encircling thecore 94 which is adapted to lift the valve head 89 when the said windingis energized. The solenoid is operated by means of relay 91. This relayincludes a winding 98 and an armature 99 adapted to be attracted by thecore ID! of said relay when the winding 68 is energized. A contact I92is adapted to be engaged by the armature 99 when the winding 98 isenergized and to close a circuit through said contact and armature.

One end of the winding 98 of relay IOI is connected by means of aconductor I03 to the plate 82 of tube 8I. The other end of this windingis connected by means of a conductor I04 to the primary 33 oftransformer 32. A condenser I05 is connected across the conductors I03and I04 by means of conductors I06 and I01. Winding 96 of solenoid 95 isconnected by means of a conductor I08 to the contact I02. The other endof this winding is connected to the conductor I99 which as previouslystated is connected to the conductor 3I leading from the source ofpower. The armature 99 of relay 95 is connected to the conductor IIIpreviously referred to.

In addition to actually controlling the concentration of the solution itis possible with my invention to accurately measure and indicate theconcentration of the same. For this purpose a tube I I3 is employedwhich is similar to the tube 8| and which has a plate II4, a grid H5,and a cathode H6. The plate II4 of this tube is connected by means of aconductor I I1 to an electric meter II8. This meter may be a millivoltmeter or similar suitable device. A conductor H9 is connected to themeter H8 and to a resistor I2I. Resistor I2I is connected by means of aconductor I22 with the conductor I04 previously referred to. Forcalibrating the meter II8 a potentiometer 61 is employed which has amovable contact 10. This potentiometer is connected in parallel with thepotentiometer H. A conductor I68 connects one end of the saidpotentiometer to the conductor 52 which leads from the cathode of thetube 31. Another conductor 69 connects the other end of thepotentiometer 63' to the conductor 56 leading from the secondary 41 oftransformer 43. The movable contact 10 of the poteniometer 61 isconnected by means of a conductor I26 to a resistor I21. This resistoris connected by means of a conductor I28 to the grid II5 of tube II3. Acondenser I29 is connected by means of a conductor I3I to the conductor28 and by means of another conductor I32 to a conductor I33. ConductorI33 in turn is connected to the cathode H6 and to the conductor I09.

Shunting the meter H8 and resistor I2I is a condenser I23. Thiscondenser is connected by means of a conductor I24 to the conductor I22and by means of a conductor I25 to the conductor II1.

A method of operation of the meter H8 is as follows: A portion of thecurrent rectified by the rectifier 31 and being the resultant of the twocurrents produced thereby is impressed upon the potentiometer 61. Thiscurrent is applied to the grid II5 of the tube I I3 which in turn isamplified by the said tube and the output of the said tube is impressedupon the meter H8. The potentiometer 61 serves to calibrate the meter H8and to cause the same to indicate the correct concentration of thesolution.

While no wiring has been shown for energizing the filaments of thevarious tubes of the invention it can readily be comprehended that saidtubes may be connected to suitable circuits energized from the winding35 of the transformer 32.

For the purpose of indicating whether the valve 85 is open or closed apilot lamp I34 is employed. This lamp is connected by means ofconductors I35 and 38 to the conductors I08 and I09 and is in parallelwith the winding 95 of the solenoid 95.

In the use of the invention the control unit it is inserted into thesolution whose concentration is to be controlled and/or measured. TubuleI9 being of metal rapidly conducts the heat from the solution to or fromthe resistor 23 bringing said resistor at substantially the sametemperature as that of the solution. Resistor 50 is used for ad justingthe value of the resistance in the branch of the circuit containingresistor 23 so that the current passing through the said resistor whentransformed and rectified just ofisets the current produced in the unitthrough the electrodes 19 and 15. In this manner no energization of therelay 9'! occurs and the valves 86 remain closed. After the solution hasbeen used for a while the concentration of the same becomes less and thediiTerence between the currents rectified by the tube 3'! will place aload upon the tube 8! which will actuate relay 9? and cause the valve 86to open. Concentrated solution now flows into the {.1

the solution varies the resistance of the compen- 1w."

sating resistor 23 varies approximately the same as the impedance of thesolution between the electrodes 15 and i9. Thus, the same results areproduced for the same concentration with varia tions in temperature andthe apparatus operates 4 in identically the same manner regardless oftemperature. If the operator desires a different concentration thepotentiometer H is adjusted and may be set to give the desiredconcentration. Since the tube 8| operates only when the voltage on thegrid is substantially positive it will readily be comprehended that therelay 95 will never operate when the concentration exceeds that forwhich the device is set since increase in the concentration of theliquid merely makes the potential on the grid of said tube morenegative. While the relay 9'! is automatically procuring the desiredconcentration of the solution, the concentration of the solution is alsoindicated by the meter H8 so that the operator may readily determinevisually the condition of the solution.

The advantages of the invention are manifest. The apparatus functionsautomatically to control the concentration of a solution and at the sametime indicates by visual means the condition of the solution. Theindicating meter if desired may be situated remotely from the apparatusso that a person not at the locality of the solution may at all times beadvised of the condition of the solution. The apparatus is simple inconstruction and positive in action. The apparatus requires noparticular skill of the operator and automatically maintains theconcentration of the solution as desired. With my invention changes inthe impedance of the solution as produced by temperature changes iscompensated for so that no correction of readings of the meter need bemade and so that the solution will automatically have the properconcentration regardless of temperature. With my invention the objectionof electrolysis is entirely eliminated. The two currents used with theapparatus in the determining of the concentration is proper so that anordinary relay may be readily operated from the resultant of the currentcombined.

Changes in the specific form of my invention, as herein described, maybe made within the scope of what is claimed without departing from thespirit of my invention.

Having described my invention, what I claim as new and desire to protectby Letters Patent is:

Apparatus responsive to the electrical impedance of solutions variableupon change in concentration and upon change in temperature at anyconcentration, said apparatus comprising a pair of spaced electrodesmaking electrical contact with the solution, a compensating resistordisposed in the solution and subject to the temperature thereof, meansfor causing the flow of alternating current through said resistor andthrough said electrodes, transformers for separately stepping up saidcurrents, rectifying means for separately rectifying the stepped upcurrents, circuits connected to said rectifier and through which therectified currents flow, a loading device comprising two resistors, saidresistors being connected in series and each being connected in one ofsaid circuits, said circuits being arranged so that the currents throughsaid resistors oppose one another and current responsive means energizedby the current flowing through said resistors.

RAYMOND V. KLINE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,399,181 Bascom Dec. 6, 19211,450,023 Edelman Mar. 27, 1923 1,701,331 Merrill Feb. 5, 1929 1,912,188Gann May 30, 1933 2,269,152 Hathaway Jan. 6, 1942 2,330,394 Stuart Sept.28, 1943 2,371,636 McConnell Mar. 20, 1945 2,372,056 Broding Mar. 20,1945 2,450,459 Thomson Oct. 5, 1948

